After a cold or hot water supply is shut off.
Intermittent noise in attic after outside spigot turned on.
If you re still stumped i would turn off the house s water and check for visible water damage throughout the home and look for water pooling in the yard around the outside of the house or in.
Supply pipe leaks may be continuous and thus are eventually discovered by water stains or mold or intermittent such as a leak around a tub or shower control that drips into the wall cavity only when the valve is turned on.
Installing insulation and anchor strapping around the pipe within the wall can usually fix the problem.
It usually occurs at one of these 4 times.
First turn off the water to the faucet.
An outdoor faucet that makes a loud vibrating noise when it s turned on or off probably has a worn out faucet washer.
Open your faucets to drain all of the water from your plumbing system.
It would get louder as more power was being used.
You may also notice sputtering as the air bubble travels.
Alternatively if the water pressure is higher than what the pipes are used to the same shrill sound can occur.
Frustrated by the loud knocking noises coming from your pipes.
A drain piping leak inside of a building cavity can also produce a noise that is hard to track down.
Turn the water back on.
We had a buzzing sound in the winter that turned out to be the electric meter.
You can easily replace it without removing the entire outdoor water faucet.
The sound can occur whether hot water is flowing out of a faucet or going down a drain.
Turn off the water supply to your house at the main supply or street level.
While cold water is running.
Every winter when it would be 20deg or below the meter would hum.
Banging pipes when the water is turned off is an example of water hammer.
Draining the water system to get water out of the vertical air chambers or installing water hammer arrestors can solve this problem.
Install water hammer arrestors.
Both of these issues can occur for several reasons so you may need a professional to evaluate and address the problem.
What s most likely causing the problem depends on when you hear the knocking sound.
If banging is caused by air in the pipes the noise will mostly occur right when you first turn on a faucet.
In faucets something as simple as a slack washer or untightened screw at the base of the faucet can result in high pitched screeching due to the tremors.
